Fundamental understanding of nanomanufacturing process consistency and the mechanical field assisted organization of a nanoconfined molecular medium

Various applications of nanomanufacturing processes and related nanosystems demand sub-10 nm scale 3-dimensional (3D) machining on non-silicon and non-polymeric materials. To address such a need, a non-contact nanoscale electro-machining (nano-EM) process using scanning tunneling microscope (STM) had been developed to function on electrically conducting and semi-conducting substrates. The nano-EM process relies on the breakdown of a dielectric molecular medium across a cathode nano-tool and anode workpiece (user-defined gap) under high (108-109 V/m) electric field strength. When an electric field is applied, tunneling electrons cause precise ejection of anodic workpiece atoms, creating tiny pores.;The mechanisms underlying this material removal are not clearly understood because of the working-scale involved and complex processes occurring simultaneously during machining. A strong understanding of these mechanisms is required in order to scale up nano-EM as a nanomanufacturing process such that sub-10 nm features can be consistently machined at ambient conditions and relatively cheap operational costs. This research project focuses to better understand the scientific rationale behind the nano-EM process mechanism through experiments, supplemented by molecular dynamics (MD) simulations.;Process consistency (repeatability) studies have been performed in this research for analyzing the commercial scaling-up prospects of nano-EM along with the effect of the nano-tool wear on the process performance. As analyzing the organizational behavior of the n-decane molecular medium under electro-mechanical boundary conditions during nano-EM is experimentally challenging, MD simulations have been performed mimicking experimental conditions to investigate this issue using a 'united-atom' model as approached while modeling polymer and alkane systems.;Results indicate that the nano-EM process spread is <20%, showing great potential for process scale-up. The use of electrochemically etched nano-tool cathodes gives superior machining performance as compared with its mechanically sheared counterparts. Through MD simulations, to corroborate the hypothesis of 'quasi-solid' behavior of n-decane medium, we have found up to four-fold increase in its maximum density under mechanical boundary conditions alone, presented with the radial distribution function curves as well. The n-decane chains also show preferred orientation in certain crystallographic directions parallel to the workpiece surface. The introduction of ledges deliberately in the cathode-anode separation also indicates preferred orientation of the n-decane chains towards the edges of the ledges.